﻿<!DOCTYPE html>
<html>
<head>
  <title>Tapered Links</title>
  <!-- Copyright 1998-2020 by Northwoods Software Corporation. -->
  <meta name="description" content="A Link class using a custom tapered geometry by overriding Link.makeGeometry." />
  <meta name="viewport" content="width=device-width, initial-scale=1">

  <script src="../release/go.js"></script>
  <script src="../assets/js/goSamples.js"></script>  <!-- this is only for the GoJS Samples framework -->

  <script id="code">
    function init() {
      if (window.goSamples) goSamples();  // init for these samples -- you don't need to call this
      var $ = go.GraphObject.make;

      myDiagram =
        $(go.Diagram, "myDiagramDiv", // the ID of the DIV HTML element
          {
            layout: $(go.ForceDirectedLayout),
            "undoManager.isEnabled": true
          });

      // This controls whether links overlap each other at each side of the node,
      // or if the links are spread out on each side of the node.
      var SPREADLINKS = true;  // must be set before defining templates!

      myDiagram.nodeTemplate =
        $(go.Node, go.Panel.Auto,
          { locationSpot: go.Spot.Center },
          $(go.Shape,
            {
              figure: "RoundedRectangle",
              parameter1: 10,
              fill: "orange",  // default fill color
              portId: "",
              fromLinkable: true,
              fromSpot: (SPREADLINKS ? go.Spot.AllSides : go.Spot.None),
              toLinkable: true,
              toSpot: (SPREADLINKS ? go.Spot.AllSides : go.Spot.None),
              cursor: "pointer"
            },
            new go.Binding("fill", "color")),
          $(go.TextBlock,
            { margin: 10, font: "bold 12pt sans-serif" },
            new go.Binding("text"))
        );

      myDiagram.linkTemplate =
        $(TaperedLink,  // subclass of Link, defined below
          go.Link.Bezier,
          (SPREADLINKS ? go.Link.None : go.Link.Orthogonal),
          {
            fromEndSegmentLength: (SPREADLINKS ? 50 : 1),
            toEndSegmentLength: (SPREADLINKS ? 50 : 1),
            relinkableFrom: true,
            relinkableTo: true
          },
          $(go.Shape,
            { stroke: null, strokeWidth: 0 },
            new go.Binding("fill", "color"))
        );

      // create a few nodes and links
      myDiagram.model = new go.GraphLinksModel([
        { key: 1, text: "one", color: "lightyellow" },
        { key: 2, text: "two", color: "brown" },
        { key: 3, text: "three", color: "green" },
        { key: 4, text: "four", color: "slateblue" },
        { key: 5, text: "five", color: "aquamarine" },
        { key: 6, text: "six", color: "lightgreen" },
        { key: 7, text: "seven" }
      ], [
          { from: 5, to: 6, color: "orange" },
          { from: 1, to: 2, color: "red" },
          { from: 1, to: 3, color: "blue" },
          { from: 1, to: 4, color: "goldenrod" },
          { from: 2, to: 5, color: "fuchsia" },
          { from: 3, to: 5, color: "green" },
          { from: 4, to: 5, color: "black" },
          { from: 6, to: 7 }
        ]);
    }


    function TaperedLink() {
      go.Link.call(this);
    }
    go.Diagram.inherit(TaperedLink, go.Link);

    // produce a Geometry from the Link's route
    TaperedLink.prototype.makeGeometry = function() {
      // maybe use the standard geometry for this route, instead?
      var numpts = this.pointsCount;
      if (numpts < 4 || this.computeCurve() !== go.Link.Bezier) {
        return go.Link.prototype.makeGeometry.call(this);
      }

      var p0 = this.getPoint(0);
      var p1 = this.getPoint((numpts > 4) ? 2 : 1);
      var p2 = this.getPoint((numpts > 4) ? numpts - 3 : 2);
      var p3 = this.getPoint(numpts - 1);
      var fromHoriz = Math.abs(p0.y - p1.y) < Math.abs(p0.x - p1.x);
      var toHoriz = Math.abs(p2.y - p3.y) < Math.abs(p2.x - p3.x);

      var p0x = p0.x + (fromHoriz ? 0 : -4);
      var p0y = p0.y + (fromHoriz ? -4 : 0);
      var p1x = p1.x + (fromHoriz ? 0 : -3);
      var p1y = p1.y + (fromHoriz ? -3 : 0);
      var p2x = p2.x + (toHoriz ? 0 : -2);
      var p2y = p2.y + (toHoriz ? -2 : 0);
      var p3x = p3.x + (toHoriz ? 0 : -1);
      var p3y = p3.y + (toHoriz ? -1 : 0);

      var fig = new go.PathFigure(p0x, p0y, true);  // filled
      fig.add(new go.PathSegment(go.PathSegment.Bezier, p3x, p3y, p1x, p1y, p2x, p2y));

      p0x = p0.x + (fromHoriz ? 0 : 4);
      p0y = p0.y + (fromHoriz ? 4 : 0);
      p1x = p1.x + (fromHoriz ? 0 : 3);
      p1y = p1.y + (fromHoriz ? 3 : 0);
      p2x = p2.x + (toHoriz ? 0 : 2);
      p2y = p2.y + (toHoriz ? 2 : 0);
      p3x = p3.x + (toHoriz ? 0 : 1);
      p3y = p3.y + (toHoriz ? 1 : 0);
      fig.add(new go.PathSegment(go.PathSegment.Line, p3x, p3y));
      fig.add(new go.PathSegment(go.PathSegment.Bezier, p0x, p0y, p2x, p2y, p1x, p1y).close());

      var geo = new go.Geometry();
      geo.add(fig);
      geo.normalize();
      return geo;
    };
    // end TaperedLink class
  </script>
</head>
<body onload="init()">
<div id="sample">
  <div id="myDiagramDiv" style="border: solid 1px black; width:100%; height:700px; min-width: 200px"></div>
  <p>
  This sample demonstrates customization of the <a>Link</a> <a>Shape</a>'s <a>Geometry</a>.
  </p>
  <p>
  The TaperedLink class in this sample inherits from Link and overrides the makeGeometry method.
  For Bezier-curve Links, this computes a Geometry that is thick at the "from" end and thin at the "to" end.
  The implementation is very simple and does not account for links that
  are coming out from a node at angles that are not a multiple of 90 degrees.
  </p>
</div>
</body>
</html>
